Conventional full-size sanitary protection and feminine hygiene products such as sanitary napkins, adult incontinence devices, etc., typically contain an absorbent element, a fluid-pervious body-contacting element and a fluid-impervious undergarment-facing element. These articles are intended to absorb body fluid from the wearer and retain the fluid in order to prevent the fluid from soiling the wearer's garments. Unfortunately, conventional feminine hygiene articles do not adequately fulfill women's protection requirements. Sanitary napkins generally have the capability of absorbing between 50 and 100 grams of fluid. However, soiling of a wearer's garments still occurs even when only 5 to 10 grams of fluid have been deposited on the absorbent articles. One of the primary reasons why soiling occurs is that conventional napkins do not properly conform to the perineal area of a woman's body. When there is a space between the user and the pad, body fluid exudate tends to travel along the contours of the body and results in soiling of the undergarment.
One factor that contributes to poor fit and lack of conformity is napkin instability. When a compression force is applied to a sanitary napkin (e.g., by the lateral compressive forces of a user's thighs), the napkin tends to fold or bunch resulting in a smaller area of contact with the user's body resulting in a gap between the absorbent article and the user's body. The napkin center may also become depressed, i.e., move in a direction downward and away from the user's body. Fluid may then travel along the body and bypass the napkin resulting in soiling of the undergarment.
An additional factor that contributes to poor fit centers on the misconception that the outer genital area of females, longitudinally between the thighs in the areas of the urethral and vaginal openings, is curved; when in fact it is essentially flat or planar. Thus, there has been a tendency on the part of some inventors to develop curved products. For example, U.S. Pat. No. 4,770,657 to Ellis describes a curved sanitary napkin with elasticized side edges.
The prior art includes examples of absorbent systems which attempt to address the soiling problem in different ways. One method is to create a resilient and/or stabilized absorbent system in order to prevent the napkin from bunching when worn. For example, U.S. Pat. No. 4,195,634 to DiSalvo describes a "stiffener means" which is incorporated into the napkin and positioned between the absorbent core and the barrier along the entire length of the pad to resist side compression. However, the stiffening/stabilizing element is located below the absorbent medium. The absorbent medium tends to collapse when exposed to fluid, causing it to move away from the wearer, despite the presence of the stiffener means. Furthermore, since the stiffener means is not conformable, it does not adapt to the body.
Other attempts to address the problems of bunching and absorbent collapse have suggested an increase in the thickness of the central portion of the absorbent element.
Fluid migration along the body is a key element of soiling. Fluid migration generally occurs when fluid is not immediately absorbed into an absorbent article. Therefore, what is needed is an absorbent article that maintains good contact with the body to lessen the likelihood that fluid will leak or migrate away from the absorbent article and cause soiling.